They appear to have come into this country freely and legally,
months or even years ago. They lived in ethnically diverse
communities like the New Jersey suburbs of New York City, San Diego,
Calif., and Hollywood, Fla., where they were able to rent apartments,
go to flight-training schools, buy cars and move money with impunity.
They were hiding in plain sight.

More vigilance by law-enforcement officials might have stopped
some of the 19 men who are believed to have killed more than 5,000
people by hijacking four airplanes and crashing three of them into
the World Trade Center and the Pentagon. Government officials now
acknowledge that two hijackers were put on a watch list in August
because of ties to a suspect in the attack on the USS Cole in the
Yemeni port of Aden. But more-vigilant law enforcement is unlikely to
have caught all of them. Officials continue to believe that there may
be more such terrorists out there. And it's difficult to imagine how
to prevent them from operating here in the future without making the
nation less free, less open and less tolerant of outsiders.

Already, the massive investigation involving 4,000 Federal Bureau
of Investigation agents and armies of local law-enforcement officials
is challenging those values. The once-fierce national debate over
"racial profiling" has been laid aside, as law enforcement officials
detain dozens of people of Middle Eastern origin -- most of whom
appear to have had nothing to do with the terrorist event. The
national discussion about easing immigration rules, launched by the
Bush administration, has been shelved. Instead the Immigration and
Naturalization Service has severely tightened security at the
nation's borders, and members of Congress are calling for a permanent
toughening of border controls. The FBI's power to police the Internet
is also likely to increase.

Over the weekend authorities chased down numerous leads around the
globe, while staying alert to the possibility that other associates
of the terrorists may still be living in this country and planning
more attacks. The FBI said two men are under arrest in New York as
material witnesses and are being held on sealed warrants. A
law-enforcement official confirmed that one was the same man who was
detained in New York's Kennedy Airport Thursday after showing a
fictitious pilot's license. A Justice Department official said a
grand jury is hearing evidence on the hijacking case in New York.

Authorities have also transferred to New York Zacarias Moussaoui,
a 31-year-old Algerian who had been apprehended last month while
taking courses at a Pan Am International Flight Academy outside
Minneapolis. He was first detained for immigration violations Aug. 17
after arousing an instructor's suspicion, reportedly because he was a
novice pilot seeking simulator training to fly commercial
aircraft.

Before going to Minnesota, Mr. Moussaoui had enrolled for several
months this spring at Airman Flight School in Norman, Okla., where
officials viewed him as a marginal pilot who quit without completing
the prescribed training. A spokesman for the French Interior
Ministry, which has been helping the FBI, said Mr. Moussaoui was on a
watch list there because he had made several trips to Afghanistan,
though he was not charged with any crime.

Meanwhile, Americans of Middle Eastern descent are reporting
harassment in their communities. Sgt. Mark Renkens, a spokesman for
the Palm Bay, Fla., police, says his department is on special alert
to patrol 7-11 convenience stores, where some franchisees of Middle
Eastern extraction have been threatened.

For some, the first frantic hours of the investigation -- as
authorities rushed to chase fresh leads and possibly prevent further
bloodshed -- may have felt like a form of harassment. Almost
immediately after the attacks, investigators from the FBI, with
journalists hot on their heels, launched an extraordinary nationwide
hunt to identify anyone with any link, however remote, to the
apparent hijackers. Reporters swarmed any address visited by FBI
agents and other locations that appeared in electronic public-record
databases to be related to people with names similar to the
hijackers.

In that mad rush to identify the villains, several men of Middle
Eastern descent appear to have been widely and wrongly identified as
members of the hijack squads. One of those was Abdulrahman Alomari, a
Saudi Arabian pilot and family man who had studied at Florida's
FlightSafety Academy International in Florida, then left, telling
neighbors he and his family were returning to their home country.
Newspaper and television reports over the weekend cited Mr. Alomari
as a suspected terrorist and quoted his neighbors at length. However,
the man FBI officials are looking for is Abdulaziz Alomari, and
investigators now think that Abdulrahman Alomari is, in fact, living
with his family in Saudi Arabia and was not a hijacker.

A neighbor ensnared

The Alomari connection also ensnared one of his neighbors, Adnan
Bukhari, who was also a student at FlightSafety. After FBI agents
searched the homes of Mr. Bukhari and Mr. Alomari, news reports
pinned Mr. Bukhari, as well as a brother named Ameer, as hijackers
killed in the crashes. The truth was Adnan Bukhari was alive and
being questioned by the FBI. Ameer Bukhari had died in an unrelated
plane crash one year earlier. (The Wall Street Journal reported that
the homes of Mr. Bukhari and Mr. Alomari had been searched and that
the FBI believed Mr. Bukhari was a possible "associate" of the
hijackers, but the paper never identified either of the men as
hijackers.)

So far, the "black box" recorders recovered from the flights that
crashed into the Pentagon and rural Pennsylvania haven't provided
many new insights; preliminary analysis has retrieved scant
information from either the voice- or the data-recorder pulled out of
the Pennsylvania wreck, officials said, and the Pentagon recorders
were badly charred.

While most of the 19 hijackers seem to have lived in this country
under little suspicion, two of the terrorists who hijacked American
Airlines Flight 77, which crashed into the Pentagon, were on a
nationwide law-enforcement watch list at the time of the hijacking.
In January 2000, U.S. intelligence videotaped a meeting in Malaysia
that was attended by an Islamic militant who later that year was
implicated in the Cole bombing, and by Khalid Al Midhar, who was one
of the terrorists on American Airlines Flight 77, according to a
senior U.S. official. In late August, U.S. intelligence recommended
putting Mr. Al-Midhar on the U.S. immigration watch list. Nawaf
Alhazmi, who is believed to have accompanied Mr. Al-Midhar on Flight
77, was also put on the list because he often was seen with Mr.
Al-Midhar.

Once the two names went to the INS, however, word came back that
both men had entered the country two months earlier. U.S. officials
say there was an effort to find them, but it consisted of little more
than entering their names in a nationwide law enforcement database
that would have triggered red flags if they were taken into custody
for some other reason. An FBI official in San Diego confirmed that
local agents weren't alerted to the status of the two men on the
watch list, even though they had entered the U.S. through Los Angeles
International Airport.

In fact, public records suggest that Mr. Alhazmi may have been
living in San Diego as early as 1996. He and Mr. Al-Midhar evidently
lived together last year at the Parkwood Apartments, a low-slung
complex in the Clairemont neighborhood, less than half a mile from
the Islamic Center of San Diego. Then they linked up with a prominent
member of the local Islamic community, Abdussattar Shaikh, who told
reporters that after he met the two men at a mosque, he invited them
to come live with him for a time at his home in the suburb of Lemon
Grove. Jeff Thurman, a spokesman for the FBI in San Diego, said
yesterday that Mr. Shaikh is "not a suspect" in the case.

Neighbors say the two men were polite and kept to themselves.
"They fit in just fine," says Marna Adair, who lives next door to Mr.
Shaikh. Another neighbor, Debbie Fortner, recalls a day last
September when Mr. Al-Midhar and Mr. Alhazmi helped other men in the
neighborhood rake leaves and put them in trash bags.

Mr. Shaikh told the San Diego Union-Tribune that Mr. Al-Midhar
lived with him for just one month, and then returned to Saudi Arabia
to see his baby daughter. Mr. Alhazmi, he said, stayed for four
months, until December 2000. He added that he spoke to Mr.
Alhazmiearly this year and that he was in Arizona studying to be a
pilot.

Mr. Alhazmi and a man named Salem Alhazmi, who may be related,
showed up this summer in New Jersey, where they paid $60 to reserve a
box at a Mailboxes Etc. outlet in a shopping plaza in Fort Lee.
Authorities believe the Alhazmis lived near the shopping plaza and
frequented diners, bakeries and coffee shops in the area. On Sunday,
just two days before they are suspected of boarding American Airlines
Flight 77 at Washington's Dulles airport, they visited Willowbrook
Mall in Wayne, N.J., where they bought sunglasses and two
weight-lifting belts at Champs Sports. "They were apparently very
concerned about the width of the belts," according to one worker at
the mall.

It's not clear what the weight-lifting belts might have been used
for. But a passenger on United Airlines Flight 93, which crashed in
Pennsylvania, indicated in a cellphone call that he and other
passengers planned to tackle a hijacker who claimed to have a bomb
strapped to his waist.

Florida appears to have been the launching ground for most of the
terrorists. Waleed M. Alshehri, who investigators believe helped
hijack American Airlines Flight 11, the first to slam into the World
Trade Center, checked into the beachfront Bimini Motel &
Apartments in Hollywood, Fla., in May of this year. Joanne Solic,
owner of the motel, said he and another man of Middle-Eastern descent
lived there for four weeks. "These guys in jeans and T shirts just
didn't stand out," she said. "They said 'Hello' and 'Goodbye,' very
polite." She said they paid their bill in cash.

The homing inn

Mr. Alshehri obtained a Florida driver's license using the Bimini
as his address, according to public records. Then on June 21, he
checked into the Homing Inn in Boynton Beach with two companions for
a month-long stay. His roommates appear to have been Satam Al Suqami,
25, and Wail Ashehri, 28, who helped in the hijacking of Flight 11.
Both Mr. Al Suqami and Mr. Ashehri also obtained Florida
identification using the Homing Inn as their address. A housekeeper
at the motel says the three men weren't very friendly. "They didn't
want their room cleaned so I don't think I went there except maybe
once when they first got there. They appeared not to speak much
English and they never waved or smiled or anything."

Ziad Jarrah, age 26, believed to be the hijacker who piloted the
plane that crashed in Pennsylvania, showed up in Hollywood, Fla., in
late April and rented the front apartment in a house at 1816 Harding
St. for $165 a week. His appearance in Hollywood coincided closely
with the arrival of Mohammed Atta and Marwan Al-Shehhi -- the two
terrorists who were identified by authorities last Thursday, and who
were on American Airlines Flight 11 and United Airlines Flight 175,
respectively.

On May 2, Mr. Jarrah obtained a Florida driver's license, and 10
days later registered a decade-old red Mitsubishi Eclipse. Later, he
relocated to a house in Lauderdale-by-the-Sea, where he was
apparently living with suspected hijacker Ahmed Alhaznawi, who is
believed to have joined him in his suicidal flight that ended with
the crash in Pennsylvania. News reports from Lebanon say Mr. Jarrah
was the scion of a wealthy Lebanese family who left the country to
study aviation in Germany.

While many of the terrorists went to flight school in the U.S.,
they don't appear to have been model students. Mark Mikarts, an
instructor at Huffman Aviation International Inc. in Venice, Fla.,
where Messrs. Atta and Al-Shehhi trained together, recalls Mr. Atta
didn't take instruction well. "He had big problems with authority,"
says Mr. Mikarts.

The two men particularly raised hackles last year when they flew a
Piper Warrior into a Miami area airport, stalled on the runway, and
then instead of radioing the tower for instructions, got out of the
plane and walked across an active runway.

Dale Kraus, then the general manager at Huffman, says he received
a phone call from an angry control-tower chief. "You don't go walking
across active taxiways at a major airport," says Mr. Kraus.

The two men had similarly bad experiences at Jones Aviation in
Sarasota, Fla., where they also took lessons. Gary Jones, the owner,
says the pair didn't take directions well. "They wanted to do it
their way," he says. "They had bad attitudes." Mr. Jones asked them
to leave, and they did -- in October of last year.

Likewise, Hani Hanjour, who the FBI believes to have piloted the
airplane that flew into the Pentagon, was a less than ideal student.
Duncan K.M. Hastie, the president of CRM Airline Training Center in
Scottsdale, Ariz., had a student named Hani Hanjoor who is believed
to be the same man, and who took courses at the center in 1996 and
1997. "He was a weak student, and instructors were not really happy
with him," recalls Mr. Hastie. He never received his pilot's
certificate from the Scottsdale training center -- then known as
Cockpit Resource Management -- and spent only $4,800 on his classes,
instead of the roughly $35,000 that would have been necessary to get
a certificate.

Commercial license

Mr. Hanjoor evidently did complete his flight instruction at
another school, though just where isn't clear. According to Federal
Aviation Administration records, a Hani Saleh Hanjoor of Saudi Arabia
was approved in 1999 to fly multiengine commercial aircraft.

Early last year, Mr. Hastie said, Mr. Hanjoor called him to
request more-advanced training. Mr. Hastie turned him down. "We pride
ourselves on training very safe and capable pilots."

Even in Florida, where many went for flight training, the
hijackers lived in twos and threes at different locations and moved
frequently, according to law enforcement officials.

One national security official compared the hijackers tactics with
those commonly used by the Soviets during the Cold War, when their
intelligence agents would spend apparently normal lives in the U.S.
before activating their espionage careers. "They adopted the KGB
approach of creating a sleeper network," said the official.

Another sign that the hijackers were skilled at avoiding any law
enforcement scrutiny is the way they moved money. Investigators have
traced cash transfers of unknown origin from overseas that went into
bank accounts controlled by the men. Once in the U.S., however,
further cash transfers took place but always in amounts below the
$10,000 threshold above which banks must report the transfers to U.S.
law enforcement, a senior official said.

In reconstructing their activities, the FBI is beginning to see
signs of their malevolent intentions. An official said that the men
conducted several dry-runs in the months before the hijackings. They
bought one-way tickets on long flights and they rented cars and took
them back the next day -- in part, authorities believe, to see if
their activities generated any attention from authorities.

The FBI is still checking how the men smuggled the box cutters
they used aboard the flights. But some investigators believe they
simply walked through security without detection, having proved to
themselves that they could do so in the dry-runs.

Meticulous even in preparing for death, Mr. Atta left his will --
not a suicide note -- in a bag found in Boston's Logan airport by
investigators, according to a U.S. official. It was dated several
years back and witnessed by a lawyer.